Upgrade Companies page: stats, delete, status badge, dropdown menu

Server:
- companyService.stats() returns per-company agent/issue counts in one query pair
- companyService.remove() cascades deletes across all child tables in dependency order
- GET /companies/stats endpoint (board-accessible)
- DELETE /companies/:companyId endpoint (board-only)

UI:
- Companies page shows agent count, issue count, spend/budget, and created-at per card
- Company status shown as a colored badge (active/paused/archived)
- Three-dot dropdown menu with Rename and Delete Company actions
- Inline delete confirmation to prevent accidental data loss
- 'New Company' button opens onboarding wizard instead of inline form

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/src/api/companies.ts

@@ -1,9 +1,12 @@
 import type { Company } from "@paperclip/shared";
 import { api } from "./client";
 
+export type CompanyStats = Record<string, { agentCount: number; issueCount: number }>;
+
 export const companiesApi = {
   list: () => api.get<Company[]>("/companies"),
   get: (companyId: string) => api.get<Company>(`/companies/${companyId}`),
+  stats: () => api.get<CompanyStats>("/companies/stats"),
   create: (data: { name: string; description?: string | null; budgetMonthlyCents?: number }) =>
     api.post<Company>("/companies", data),
   update: (
@@ -11,4 +14,5 @@ export const companiesApi = {
     data: Partial<Pick<Company, "name" | "description" | "status" | "budgetMonthlyCents">>,
   ) => api.patch<Company>(`/companies/${companyId}`, data),
   archive: (companyId: string) => api.post<Company>(`/companies/${companyId}/archive`, {}),
+  remove: (companyId: string) => api.delete<{ ok: true }>(`/companies/${companyId}`),
 };